Electric alarm.



T. NORPOTH. BLBCTBIG ALARM.

APPLICATION FILED SEPT. 28,1908.

914,173. Patent-,ea Mar.2,19o9.

Illli i 1HE NuRRls PETER: ca'. wlxsnmcfnu. n. c.

THEODOR NORPOTH, OF ST. LOUIS, MISSOURI.

ELECTRIC ALARM.

Specification of Letters Patent.

Patented March 2, 1909.

Application led September 28, 1908. A Serial No. 455,209.

To all whom 'it may concern:

Be it known that I, THEODOR NORPOTH, citizen of the United States, residing at St. Louis, State of Missouri, have invented certain new and useful Improvements in Electric Alarms, of which the following is a full, clear, and exact description, reference being had to the accompanying drawings, forming a pant thereof.

My invention has relation to improvements in electric alarms; and it consists in the novel details of construction more fully set forth in the specication and pointed out in the claims.

In the drawings, Figure 1 is a perspective of a room showing the application of my invention; Fig. 2 is a plan of the device with part of the top wall of the casing removed; Fig. 3 is an elevation with iront wall of the casing removed; Fig. 4 is a diagrammatic view showing the oscillating lever, the contact arm and brake lever cooperating therewith, and showing in dotted outline the locked position of the parts; Fig. 5 is a perspective of the device showing the interior parts in dotted outline; and Fig. 6 is a sectional detail showing the hinged apron through which the cord passes into the casing.

The present invention is an improvement in the construction of electric alarm forming the subject-matter of my U. S. Patent 880,691 dated March 3, 1908, and while contemplating the several objects set forth in said patent, the improvement herein is simpliiied in details of construction which result in a material saving in the cost of manu facture, and which at the same time render the device less liable to get out of order, while in no wise detracting from the sensitiveness of operation.

A further object is to provide means which shall insure closing of the electric circuit which determines the alarm with the least possible degree of movement in the cord usually disturbed by the burglar.

The superior advantages of the present invention will be clearly apparent from a detailed description thereof which is as follows:

Referring to the drawings, C, represents a box or casing on top of which the annunciator bell A is mounted, a handle H being pivotally secured to the top of the boX so as to straddle the bell. Located within the casing is a battery B from one pole of which leads a wire w to one end of the energizing coil E of the annunciator, a similar wire w leading from the opposite end of the coil to a contact member mounted on an insulating block 1, said member having a fixed arm a secured to the block, and a movable resilient arm Z; having a hump or bend c near its free end for a purpose presently to appear. Projecting at right angles from the arm a and in electric connection therewith is a rigid contact arm 2 having a terminal U-shaped formation 3 the distance between the arms or members of which determines the degree of dis lacement or rotation which the rotatable dis of the device may suffer before the circuit is closed. Pivoted to the block 1 and capable of oscillation in a plane which is parallel to the plane of disposition of the loop-formation 3, is a bent brake-lever composed of the formations d, e, f, g, 7i, the pivot being at the angle between d and c, the member d having an upwardly turned terminal d projecting through a curved slot s in the top of the casing and provided with a knob or button lc by which the lever may be manipulated. For a certainportion of its oscillation, the portion e rubs up against the hump c of the resilient arm t with results presently to be referred to.

The parts just described occupy a position to one side of a rotatable disk or member 4 provided with a peripheral groove 5 for the winding and unwinding cord 6, and actuated by a spring 7 the same as in my patent referred to, the shaft 8 of the disk being carried in bearings 9, 9, from one of which leads a wire w back to the opposite pole of the battery B. Supported on the shaft 8 oppon site one face of the disk 4, is an oscillating arm or member 10, said arm forming the upper terminal of a single piece of wire looped about the shaft, the lower terminal 10 of the wire being embedded in a groove or depression formed in the shaft for a portion of its thickness, which arrangement prevents displacement ofthe wire along the shaft, yet the looping of the wire about the shaft on each side of the arm 10 serves to hold the arm 10 with suicient friction to the shaft as to insure oscillation of the arm with any rotation imparted to the disk 4. The cord 6 passes through an opening o of an apron or leaf 11 hinged to the casing wall and normally closing a cut-away section O of said wall, the opening 0 while ample to allow the cord to pass freely there through being sufficiently small to intercept a knot or ring r such as the cord 6 is provided with.

The operation of the alarm may be described as follows ln order to set the alarm, that is to say, in order to place it in condition for sounding an alarm in the event of any tampering with the cord 6, the free end of the latter is secured for example to a window sash, or screen or to a door or to any movable object liable to be disturbed by the intruder. To do this a suflieient length of cord must be unwound` from the disk Ai. ln order that this be done without closing the circuit (and thereby sounding the bell) the operator takes` hold of the knob k and swings the brake-lever (which by the way is insulated and not adapted to conduct the current into the main circuit) in a direction to bring the hook or loop g into engagement with the arm 10 (Fig. 2) in which action the arm is forced toward the disk 4 and away from between the members of the U-shaped formation 3, and held against movement and consequent engagement with any portion of the loop 3. rEhe disk 4; however, is free to turn to allow for the necessary unwinding of the cord, since the frictional engagement between the wire looped about the disk-shaft, of which wire the arm 10 forms one of the terminals, is insufficient to prevent such rotation when the cord (usually a silk thread) is pulled upon for'the purpose. The cord being attached to the desired object, the operator swings the brake-lever in opposite direction to its full limit thereby releasing the resilient arm 10 which now springs back into position between the members of the U-shaped loop 3 (Fig, 4L). lt follows therefore that upon the slightest subsequent disturbance of the cord, either by a slight pull thereon which will rotate the disk a in one direction, or by a cutting of the cord which will permit the clock spring 7 to rotate it in the opposite direction, the arm 10 will oscillate in such rotation and contact with y either one or the other side of the loop 3, and

at once close the circuit and thereby sound an alarm. ln the oscillations of the brakelever d, e, f, g, 7L in either directionrfor thc purpose of either locking the arm l0 or reeasing it, the section @of said lever rubs up against the hump c of the resilient arm t, during which rubbing the circuit is temporarily closed and the bell sounded. This detail is useful to detect any tampering on the part of the intruder with the brake-lever, for were he to swing the lever in a direction to lock the arm 10 as a precautionary measure against the closing of the circuit in the event of an accidental disturbance of the cord, the temporary contact between the hump c and section e of the lever would still sound sufficient warning to the occupants of the premises that an intruder was present. The movparallel to the mentary closing of the circuit just referred to could also be made use of to energize a coil for the attraction of an armature in which movement the armature couldA be made to close the circuit of a secondary battery operating a secondary alarm. which would keep on ringing, the same as is done in my pending application `filed June 12, 1908, Serial Number 438,186, but since this particular application of the momentary closing of the circuit is covered in said pending application no further comment need lbe made thereon in this connection.

Should the intruder on the other hand, carefully tie a knot in the cord close tothe aperture o of the apron 11, and then release the cord, the apron being hinged would readily yield to the tension of the cord under the driving action of the spring 7, and allow the disk 4 to rotate sufficiently to impart the required degree of oscillation to the arm vl() to effect contact with the loop 3 of the contact arm 2 and close the circuit. So that the present improvement is exceedingly sensitive and its purpose is not readily circumvented. Vihe mounting of the circuit-closing arm i() opposite the face of the disk 4c results in a compact construction, since in its oscillations the arm is confined to a plane substantially plane of rotation of the disk.

Having described my invention, what I claim is l. In an electric alarm, a normally open electric circuit, an annunciator or bell in the path thereof, a rotatable disk, a current conducting member secured friotionally about the disk-shaft opposite the face of the disk and moving in response to the rotation thereof, and circuit closing devices affording said member a limited movement for a rotation of the disk in either direction, substantially as set forth.

2. ln an electric alarm, a normally open electric circuit, an annunciator or bell in the path thereof, a rotatable disk, an oscillating current conducting arm secured frictionally about the disk-shaft opposite the face of the disk and moving in response to the rotation` thereof, and circuit-closing devices affording said arm a limited oscillation for a rotation of the disk in either direction, substantially as set forth.

3. ln an electric alarm, a normally open electric circuit, an annunciator or bell in the path thereof, a rotatable disk, a current-conducting member secured frictionally about the disk-shaft opposite the face of the disk and actuated by the disk-shaft, and circuitclosing devices affording a limited movement to the member for a rotation of the disk in either direction.

4. ln an electric-alarm, a normally open electric circuit, an annunciator or bell in the path of the circuit, a rotatable disk, an arm secured frictionally about the disk-shaft and oscillating therewith, devices for intercepting the oscillation of the arm for a given arc of rotation of the disk, and circuit closing means for closing the circuit upon the inter ception of the arm, substantially as set forth.

5. In an electric alarm, a normally open electric-circuit, an annunciator or bell in the path of the circuit, a rotatable disk, an arm frictionally secured about the disk-shaft and oscillating therewith, devices for intercepting the oscillation of the arm for a given arc of rotation of the disk and simultaneously closing the circuit, and means for disengaging the arm from said intercepting devices whereby the circuit is again broken, substantially as set forth.

6. In an electric alarm, a normally open electric-circuit, an annunciator or bell in the path of the circuit7 a rotatable disk, an arm frictionally secured about the disk-shaft and oscillating1 therewith, devices for intercepting the oscillation of the arm for a given arc of rotation of the disk and simultaneously closing the circuit, a brake-lever for disengaging the arm from said intercepting devices, and a contact member for momentarily engaging the brakeelever for a movement thereof in either direction, and for the time closing the circuit and sounding an alarm substantially as set forth.

7. In an electric-alarm, a normally open electric circuit, an annunciator or bell in the path thereof, a rotatable disk, an oscillating arm mounted about the axis of the disk and moving in a plane substantially parallel to the plane of rotation of the disk, and intermediate circuit-closing devices for closing the latter upon rotation of the disk and consen quent oscillation of the arm, substantially as set forth.

8. In an electric alarm, a rotatable member, an annunciator responsive thereto, a cord adapted to Wind on said rotatable mem bei', means in connection With said member for exerting a tension on the cord, and a yielding support for the cord having an open ing for the passage of the cord therethrough, but actuated by a knot formed on the cord.

9. In an electric alarm, a rotatable member, an annunciator responsive thereto, a cord adapted to Wind on said member, means in connection With said member for exerting a tension on the cord, and a hinged support for the cord having an opening for the passage of the cord therethrough but actuated by a knot formed on the cord.

In testimony whereof I my signature, in presence of tWo Witnesses.

THEODOR NORPOTII.

Vfitnesses EMiL STAREK, FANNIE E. WEBER. 

